|
Abstract
|
A many-body dissipative dynamics simulation
approach is presented for inclusion of many-body interactions in
fluid cesium. Employing this many-body potential, simulations are
done, in the grand canonical ensemble, to calculate the vapor?liquid
equilibria over a wide range of temperatures (from the melting
temperature to the critical temperature). The calculated coexisting
liquid and vapor densities and the vapor pressures are in close
agreement with experiment. The metal-nonmetal transition is
examined in terms of cluster formation in low density cesium with
increasing pressure. Our analysis of cluster formation along the
critical isotherm shows that at pressures noticeably higher than the
critical pressure very large spherical clusters are formed in the simulation box. The cluster sizes decrease with decreasing pressure
to the critical pressure. At the critical pressure, only small clusters are seen in the simulation box. The cluster structures also
change noticeably as the metal?nonmetal transition approaches. In the metallic state, high-density, spherical clusters are formed.
Decreasing the pressure to the critical pressure causes rearrangement in the structure of spherical clusters to ellipsoidal (lower
density) clusters. In the nonmetallic region, the clusters are very diffuse (low density) and do not have a well-defined structure.
Adopting the fraction of cesium atoms involved in clusters larger than a threshold size as the fraction contributing to electrical
conductivity, our simulation results well predict a sudden decrease in the electrical conductivity in close agreement with
experimental observations.
|